This study was carried out to extract essential oils from cashew shell and its kernel and to characterize the oils; with the view to ascertain their suitability for consumption and other uses. Soxhlet apparatus was used for the extraction using hexane as solvent. The physical and chemical properties of the extracted oil were analyzed. The percentage oil extracted from the shell of the cashew was found to be 25.5% while that extracted from the kernel was 11.8% oil. The results of the physical analysis showed that the cashew kernel oil (CKO) is light yellow while the Cashew Nut Shell Liquid (CNSL) is dark brown. The boiling points for shell and kernel oil were 920c and 950c respectively. The cashew kernel oil is non-toxic and the properties of CNSL conformed, to a greater extent, to that exhibited by linseed oil. This suggests its application in the processing and manufacturing industries. The kernel oil conformed both in its physical and chemical properties to those of groundnut and melon oil and thus could be used in the food and pharmaceutical industries.
1.1 BACKGROUND OF THE STUDY
Essential oils are volatile oils, which occur in some trees. Theyoccur in the leaves, blossoms, fruits, trunks, stems and/or roots of the bearing trees. However, very few of the great number of essential oil bearing species are being used for commercial production of the oils.
Though they are called oils, they are quite distinct from the traditional vegetable oils, because they are very light, non- greasy, absorbed quickly into the skin and above all, very volatile [ 1]. A number of essential oils are exploited by chemical and allied industries as a source of specific compounds for subsequent transformation to a wide range of synthetic products such as aroma chemicals, flavours, vitamins and pesticides. They are also valuable in the manufacture of essential balms, medicated ointments, soaps, perfumes, shampoos and other cosmetics. Various methods exist for the recovery of essential oils, which include mechanical expression, effleurage, maceration, steam distillation, water distillation, water and steam distillation and supercritical fluid extraction. Most essential oils currently in use by cosmetic, food, perfumery and pharmaceutical industries in Nigeria are imported. Perhaps, this is due to the fact that there are virtually little or no local manufacturers of these all-important industrial intermediates in Nigeria.
Therefore, for the aforementioned numerous uses of essential oils coupled with the high cost of their importation, significant increase in demand by chemical and allied industries and availability of abundant raw materials in Nigeria, there is the need to develop appropriate technology for local production of essential oils. This can assist in reducing the large amount of money being spent on the importation of these oils and if scaled-up to industrial level, it will also provide a base for essential oils exportation which could in turn make Nigeria improve its foreign exchange savings and earnings.
1.2 STATEMENT OF THE PROBLEM
The most important product of the cashew tree is the nut, which is used as confectionery. Cashew shell nut liquid (CNSL), which is of great industrial importance is obtained from the seed pericarp by steam distillation or extraction. When unprocessed or improperly roasted, the cashew nut is very astringent (Abitogun and Borokini, 2009); the complete roasting makes all the allergens inactive. Cashew nut is a high value edible nut which yields two “Oils” one of these found, between the seed coat or pericarp and the nuts.
Hence, this work intends to solve the problems of extraction and production of essential oil from cashew nuts.
1.3 AIM AND OBJECTIVES OF THE STUDY
The aim of this research is to investigate the extraction and production of essential oil from cashew nuts. Therefore, the specific objectives are as follows;
1. To examine the features of essential oil
2. To extract essential oil from cashew nuts
3. To determine the physical properties of the essential oil produced
4. To determine the chemical properties of the essential oil produced
1.4 SIGNIFICANCE of the study
The significance of this research cannot be overemphasized. This is because the research will reveal methods of extraction and production of essential oil from cashew nuts.
It will also benefit student of science Laboratory Technology because it serves as a secondary material for students who will be interested in similar topic.
1.5 SCOPE OF THE STUDY
Almost no significant advancements have been made for the utilization of the cashew nut. There is hardly any literature available, particularly with regard to the extraction and production of essential oil. The present research is to develop a new low-cost and effective extraction and production of the essential oil. The scope of the present investigation is as follows:
1. The features of essential oil
2. Extraction of essential oil from cashew nuts
3. The physical properties of the essential oil produced